Technical Field
This disclosure relates generally to electric motors for powering vehicles. More specifically, this disclosure relates to an electric motor disposed coaxially between a pair of clutch packs. Each clutch pack coaxially connects to and provides differential and torque vectoring to a wheel or traction member.
Description of the Related Art
Motor vehicles have traditionally employed internal combustion (IC) engines with a mechanical or hydraulic transmission system. Hybrid vehicles utilize a combination of an IC engine that powers one axle and an electric motor that powers the other axle. Fully electric cars are now available, some with electric motors mounted perpendicular to the axles, others with electric motors mounted parallel to or coaxially with one or both axles. One advantage of using electric motors for powering vehicles is that there are no combustion products to treat before emission to the atmosphere. Another advantage is that specific types of electric motors can regenerate energy via regenerative braking that provides braking while recharging the power source after release of the accelerator, thereby increasing the overall efficiency of the vehicle.
Vehicles powered by one or more electric motors require a transmission with a complex gear assembly and a differential to achieve the desired output speed and torque levels to each wheel. The differential transfers the motor torque to the wheels. Torque vectoring technology provides the differential with the ability to vary the torque transferred to each wheel. Torque vectoring enhances the ability of the wheels to grip the road for better launch and handling. An electronic slip differential (eLSD) system ensures that each wheel is receiving sufficient torque by use of an electronic control unit. An eLSD system electronically monitors input from various wheel sensors and, in the event of slippage, transfers extra torque to the wheel with the most traction.
However, providing hybrid or electric vehicles with slip differential and/or torque vectoring presents significant packaging problems because there is limited space within the rotor/stator housing of an electric motor. Thus, there is a need for an electric drive system that can provide slip differential and torque vectoring that overcomes these packaging problems.